First-Principles Investigation on the Structure of Phase III of Hydrogen

First-principles computations based on the density functional theory have been performed to search for the most stable structure of phase-III solid hydrogen. Specifically the phase diagram at zero temperature is predicted by calculating the static total energy and the zero-point motion. Our results suggest that solid hydrogen under pressures in a range of $\sim 150-300$ GPa could have lower symmetry than predicted previously. We will discuss the topological considerations on phase transitions from Phase I to II to III, and the available experimental evidences supporting current finding as well.